Lambda syntax and behavior in Python - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a lambda function in Python?

A lambda function is a small anonymous function defined with the lambda keyword. It can take any number of arguments but has only one expression, which is returned automatically.

beginner

How do you write a lambda function that adds 5 to its input?

You write it as lambda x: x + 5. This means the function takes one argument x and returns x + 5.

beginner

Can a lambda function contain multiple expressions or statements?

No, a lambda function can only contain a single expression. It cannot have multiple statements or commands like loops or assignments.

intermediate

How does a lambda function differ from a regular function defined with def?

A lambda function is anonymous (has no name) and is limited to one expression. A regular function can have multiple statements, a name, and more complex behavior.

beginner

What is the output of this code?

add = lambda x, y: x + y
print(add(3, 4))

The output is 7. The lambda function adds the two inputs 3 and 4 and returns the sum.

What keyword is used to create a lambda function in Python?

A lambda

B def

C func

D function

The lambda keyword is used to create anonymous functions in Python.

Which of the following is a valid lambda function syntax?

A def lambda(x, y): return x + y

B lambda (x, y) { return x + y }

C lambda x, y: x + y

D lambda x, y { x + y }

Option C is the correct syntax for a lambda function in Python.

What will this lambda function return?

lambda x: x * 2

A Double the input value

B Half the input value

C Always returns 2

D Returns the input unchanged

The lambda function multiplies the input by 2, so it returns double the input.

Can a lambda function have multiple statements inside it?

A Only if using semicolons

B Yes, multiple statements separated by commas

C Yes, if enclosed in parentheses

D No, only one expression is allowed

Lambda functions are limited to a single expression and cannot contain multiple statements.

What is the main use of lambda functions?

A To define classes

B To create small anonymous functions quickly

C To replace all regular functions

D To write multi-line functions

Lambda functions are mainly used for quick, small anonymous functions, often as arguments to other functions.

Explain what a lambda function is and how it differs from a regular function defined with def.

Think about the size and naming of the function.

Write a lambda function that takes two numbers and returns their product. Then explain how it works.

Use the format: lambda arguments: expression